Temporal variability of aridity in Argentina during the period 1961-2020

This paper examines the temporal variability of aridity in Argentina during the period 1961-2020. Monthly data from the Climatic Research Unit (CRU) were used to define climate types according to the Aridity Index (AI) from the United Nations Environment Programme (UNEP). Argentina presents a variety of climates ranging from arid and semiarid to subhumid and humid, suggesting simultaneous water deficit and excess conditions. However, an aridity increase in the past six decades has been observed in much of the country, contrasting with reduced areas that have become wetter. Since these changes were not uniform across the study area, a regional-level analysis was conducted to adequately capture the aridity temporal patterns, including trends, jumps, seasonality, and cycles. In general, there was a decrease in the annual AI in most regions, with non-linear patterns such as longterm oscillations, shorter-duration cycles, and abrupt variations in the average. Seasonal aridity changes showed variabilities according to the season, with higher humidity during summer and autumn, and greater aridity during winter and spring. Simultaneously, seasonal AI experienced periodic behavior with significant arid and humid cycles alternating every 10-15 years. These findings highlight the complexity of climate changes, which vary by region and season.